Solid state lighting component

ABSTRACT

An LED component according to the present invention comprising an array of LED chips mounted on a submount with the LED chips capable of emitting light in response to an electrical signal. The array can comprise LED chips emitting at two colors of light wherein the LED component emits light comprising the combination of the two colors of light. A single lens is included over the array of LED chips. The LED chip array can emit light of greater than 800 lumens with a drive current of less than 150 milli-Amps. The LED chip component can also operate at temperatures less than 3000 degrees K. In one embodiment, the LED array is in a substantially circular pattern on the submount.

This application is a continuation-in-part of, and claims the benefitof, U.S. patent application Ser. No. 11/982,275 to Keller et al., filedon Oct. 31, 2007, and is a continuation-in-part of and claims thebenefit of U.S. patent application Ser. No. 11/743,324 to Medendorp etal., filed on Sep. 27, 2007.

This invention was made with Government support under Contract No.DE-DE-FC26-06NT42932 awarded by the National Energy TechnologyLaboratory. The Government has certain rights in this invention.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to methods for solid state lighting and inparticular compact monolithic solid state lamps comprising multiplelighting elements.

Description of the Related Art

Light emitting diodes (LED or LEDs) are solid state devices that convertelectric energy to light, and generally comprise one or more activelayers of semiconductor material sandwiched between oppositely dopedlayers. When a bias is applied across the doped layers, holes andelectrons are injected into the active layer where they recombine togenerate light. Light is emitted from the active layer and from allsurfaces of the LED.

In order to use an LED chip in a circuit or other like arrangement, itis known to enclose an LED chip in a package to provide environmentaland/or mechanical protection, color selection, light focusing and thelike. An LED package also includes electrical leads, contacts or tracesfor electrically connecting the LED package to an external circuit. In atypical LED package 10 illustrated in FIG. 1a , a single LED chip 12 ismounted on a reflective cup 13 by means of a solder bond or conductiveepoxy. One or more wire bonds 11 connect the ohmic contacts of the LEDchip 12 to leads 15A and/or 15B, which may be attached to or integralwith the reflective cup 13. The reflective cup may be filled with anencapsulant material 16 which may contain a wavelength conversionmaterial such as a phosphor. Light emitted by the LED at a firstwavelength may be absorbed by the phosphor, which may responsively emitlight at a second wavelength. The entire assembly is then encapsulatedin a clear protective resin 14, which may be molded in the shape of alens to collimate the light emitted from the LED chip 12. While thereflective cup 13 may direct light in an upward direction, opticallosses may occur when the light is reflected (i.e. some light may beabsorbed by the reflector cup due to the less than 100% reflectivity ofpractical reflector surfaces). In addition, heat retention may be anissue for a package such as the package 10 shown in FIG. 1a , since itmay be difficult to extract heat through the leads 15A, 15B.

A conventional LED package 20 illustrated in FIG. 1b may be more suitedfor high power operations which may generate more heat. In the LEDpackage 20, one or more LED chips 22 are mounted onto a carrier such asa printed circuit board (PCB) carrier, substrate or submount 23. A metalreflector 24 mounted on the submount 23 surrounds the LED chip(s) 22 andreflects light emitted by the LED chips 22 away from the package 20. Thereflector 24 also provides mechanical protection to the LED chips 22.One or more wirebond connections 11 are made between ohmic contacts onthe LED chips 22 and electrical traces 25A, 25B on the submount 23. Themounted LED chips 22 are then covered with an encapsulant 26, which mayprovide environmental and mechanical protection to the chips while alsoacting as a lens. The metal reflector 24 is typically attached to thecarrier by means of a solder or epoxy bond.

Typical LED components for solid state lighting applications attempt toachieve high light output by operating single LED chips at as high aspossible current and at a low voltage typical for individual LEDs. Forhigher powered operation it may also be difficult to transfer dissipateheat generated by the LED chip 22. Submounts 23 can be made of materialssuch as ceramics that are not efficient at conducting heat. Heat fromthe LED chip passes into the submount below the LED chip, but does notefficiently spread laterally from below the LED. This increased heat canresult in reduced lifetime or failure of the package.

At the systems level high current operation necessitates relativelyexpensive drivers to provide the constant DC current source for suchcomponents. Operating SSL components at lower currents and highervoltages instead would provide for lower cost driver solutions andultimately lower system costs. This is currently achieved by assemblingmultiple LED components of a suitable current rating in series at thecircuit board level. The lower driver cost for such solutions isoutweighed by the high cost of the individual components.

Current LED packages (e.g. XLamp® LEDs provided by Cree, Inc.) can belimited in the level of input power and for some the range is 0.5 to 4Watts. Many of these conventional LED packages incorporate one LED chipand higher light output is achieved at the assembly level by mountingseveral of these LED packages onto a single circuit board. FIG. 2 showsa sectional view of one such distributed integrated LED array 30comprising a plurality of LED packages 32 mounted to a substrate orsubmount 34 to achieve higher luminous flux. Typical arrays include manyLED packages, with FIG. 2 only showing two for ease of understanding.Alternatively, higher flux components have been provided by utilizingarrays of cavities, with a single LED chip mounted in each of thecavities. (e.g. TitanTurbo™ LED Light Engines provided by Lamina, Inc.).

These LED array solutions are less compact than desired as they providefor extended non-light emitting “dead space” between adjacent LEDpackages and cavities. This dead space provides for larger devices, andcan limit the ability to shape the output beam by a single compactoptical element like a collimating lens or reflector into a particularangular distribution. This makes the construction of solid statelighting luminares that provide for directed or collimated light outputwithin the form factor of existing lamps or even smaller difficult toprovide. These present challenges in providing a compact LED lampstructure incorporating an LED component that delivers light flux levelsin the 1000 Lumen and higher range from a small optical source.

Current high operating voltage luminaire solutions integrate multiplediscrete LED components as assemblies at the circuit boards level. Toachieve the desired beam shape individual optical lenses are mountedwith each LED component, or very large reflectors (larger than the formof existing conventional sources) have to be employed. These secondaryoptical elements (lenses or reflectors) are large and costly, and theextended area of such single chip arrays further provides for a moreexpensive LED luminaire. Additionally, any light being reflected fromthe sidewalls in the packages and cavities can also result in additionaloptical losses, making these overall LED components less efficient.

SUMMARY OF THE INVENTION

One embodiment of a monolithic light emitting diode (LED) packageaccording to the present invention comprising an LED array thatgenerates light having a luminous flux greater than 800 lumens at acolor temperature less than 3000 K.

Another embodiment of an package according to the present inventioncomprises an array of LED chips arranged under a single lens in asubstantially non-rectangular layout.

Another embodiment of a monolithic LED package according to the presentinvention comprising an array of LED chips arranged in under a singlelens in an asymmetric layout.

Still another embodiment of a monolithic (LED) package according to thepresent invention comprising an array of LED chips. Each of the LEDchips emits light at a first or second color with the LED chips emittingat the first color being randomly arranged in relation to the LEDs chipsemitting at the second color.

These and other aspects and advantages of the invention will becomeapparent from the following detailed description and the accompanyingdrawings which illustrate by way of example the features of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a shows a sectional view of one embodiment of a prior art LEDlamp;

FIG. 1b shows a sectional view of another embodiment of prior art LEDlamp;

FIG. 2 shows a sectional view of one embodiment of a prior art LEDcomponent;

FIG. 3 shows a sectional view of one embodiment of an LED componentaccording to the present invention;

FIG. 4a is a sectional view of another embodiment of an LED componentaccording to the present invention;

FIG. 4b is a perspective view of the LED component shown in FIG. 4 a;

FIG. 4c is a top view of the LED component shown in FIG. 4 a;

FIG. 4d is a bottom view of the LED component shown in FIG. 4 a;

FIG. 5 is a top view of one embodiment of the die attach pads andconductive traces for an LED component according to the presentinvention;

FIG. 6a is a sectional view of still another embodiment of an LEDcomponent according to the present invention;

FIG. 6b is a detailed sectional view of a portion of the submount of theLED component shown in FIG. 6 a;

FIG. 6c is a bottom view of the LED component shown in FIG. 6 a;

FIG. 7 is a sectional view of another embodiment of an LED componentaccording to the present invention having a flat lens;

FIG. 8 is a sectional view of another embodiment of an LED componentaccording to the present invention having an aggregate optical lens;

FIG. 9 is a schematic of an LED chip interconnection for one embodimentof an LED component according to the present invention;

FIG. 10 is a graph showing the different current and voltage operatingrequirement for different embodiments of the present invention;

FIG. 11 is a schematic of an LED chip interconnection for anotherembodiment of an LED component according to the present invention; and

FIG. 12 is a schematic of an LED chip interconnection for still anotherembodiment of an LED component according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention comprises a monolithic LED component having aplurality of LED chips mounted onto a submount to create a singlecompact optical source element. As used in the present application,monolithic refers to LED components wherein the LED chips are mounted onone substrate or submount. In some embodiments, at least some of LEDchips are arranged in series electrical contact, with differentembodiments providing multiple series connected LEDs, or combinations ofseries/parallel interconnect arrangements. The present invention allowsfor LED components to be designed and selected with a particular chipsize and total LED emitting area to achieve the desired component size,and desired light output at an LED optimum current density perindividual chip. This allows the LED components to be provided with theoptimum efficiency at a particular cost. By flexibly choosing an LEDchip size the present invention provides for a component that operatesat the optimum voltage and current for the application specific, drivercost solution.

In general, LED drivers that provide output power at a lower current andhigher voltage as opposed to higher current and lower voltage canincorporate lower cost electronic components (e.g. power FETs) without areduction in driver efficiency. Depending on the particular application,it may be desirable to operate different LED components at differentlevels, such as 24V, 40V, 80V or similar. By utilizing different sizedLED chips (assuming that the chips operate at the same current density)the operating voltage of the component can be adjusted. Further,different combinations of series and parallel connections for the LEDchips on the LED component can provide the optimum system voltage andcan provide for redundancy, in case one of the LED chips fails inoperation. The different LED devices can also be driven at lower orhigher current densities. To achieve the same light output the operationat lower current density for each of the LED chips would result in ahigher LED component efficiency, but can result in the need to addadditional devices. Alternatively, a lower LED component efficiency andthe ability to remove LED devices from the array would be the result oftargeting a higher current density operation per LED chip, with thecorresponding impact on the array size. Monolithically integrated LEDchips within a single cavity or under a single lens allow for LEDcomponents to be provided at the desired light emission, withoutsubstantially increasing the optical source and component size.

By providing series connected LEDs or series/parallel connected LEDs thenumber of external contacts to the LED component can be reduced. Foreach series connection only two contacts are needed corresponding to thetwo contacts for each LED chip. In an LED component having a singleseries connected LED circuit as few as two external contacts can beutilized, and in an LED component having two series connected circuitsas few as four external contacts can be used. Utilizing series connectedLEDs potentially also allows for a reduced number of electrostaticdischarge (ESD) protection chips, with a single ESD chip of a suitableclamp voltage providing protection for multiple LED chips in each seriesconnected circuit, as opposed to a system solution that incorporates amultitude of LED lamps, which could require an ESD chip within eachlamp. For an LED component having a single series connected circuit,potentially a single ESD chip can be used.

The LED components according to the present invention can be designed tooperate at different luminous flux. They can be also designed to emitwhite light at different color temperatures. In other embodiments, theLED components according to the present invention can operate at colortemperatures from about 6000 K down to about 2700 K. In one embodimentthe monolithic LED component operates with a multiple color LED chiparray producing a white luminous flux greater than 800 lumens at a colortemperature less than 3000 K. The LED component comprises LED emitterchips that can be operated at favorable current and current density toallow for operation using low cost, high power efficiency emitters. Inone embodiment the current can be less that 150 mA, such as, forexample, in the range of approximately 50 to less than 150 mA. Differentsized LED chips can be used at this current range and emitters ofvarious sizes could be integrated in the array.

The present invention is described herein with reference to certainembodiments but it is understood that the invention can be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. In particular, the present invention isdescribed below in regards to arrays of LEDs in differentconfigurations, but it is understood that the present invention can beused many other array configurations to using other solid stateemitters. The components can have different shapes and sizes beyondthose shown and different numbers of LEDs can be included in the arrays.Some or all of the LEDs in the arrays can be coated with adown-converter coating that typically comprises a phosphor loaded binder(“phosphor/binder coating”), but it is understood that the presentinvention can be used to coat LEDs with other materials fordown-conversion, protection, light extraction or scattering.

It is also understood that the phosphor binder can have scattering orlight extraction particles or materials, and that the coating can beelectrically active. Additionally, single or multiple coatings and/orlayers can be formed on the LEDs. A coating can include no phosphors,one or more phosphors, scattering particles and/or other materials. Acoating may also comprise a material such as an organic dye thatprovides down-conversion. With multiple coatings and/or layers, each onecan include different phosphors, different scattering particles,different optical properties, such as transparency, index of refraction,and/or different physical properties, as compared to other layers and/orcoatings.

It is also understood that when an element such as a layer, region orsubstrate is referred to as being “on” another element, it can bedirectly on the other element or intervening elements may also bepresent. Furthermore, relative terms such as “inner”, “outer”, “upper”,“above”, “lower”, “beneath”, and “below”, and similar terms, may be usedherein to describe a relationship of one layer or another region. It isunderstood that these terms are intended to encompass differentorientations of the device in addition to the orientation depicted inthe figures.

Although the terms first, second, etc. may be used herein to describevarious elements, components, regions, layers and/or sections, theseelements, components, regions, layers and/or sections should not belimited by these terms. These terms are only used to distinguish oneelement, component, region, layer or section from another region, layeror section. Thus, a first element, component, region, layer or sectiondiscussed below could be termed a second element, component, region,layer or section without departing from the teachings of the presentinvention.

Embodiments of the invention are described herein with reference tocross-sectional view illustrations that are schematic illustrations ofembodiments of the invention. As such, the actual thickness of thelayers can be different, and variations from the shapes of theillustrations as a result, for example, of manufacturing techniquesand/or tolerances are expected. Embodiments of the invention should notbe construed as limited to the particular shapes of the regionsillustrated herein but are to include deviations in shapes that result,for example, from manufacturing. A region illustrated or described assquare or rectangular will typically have rounded or curved features dueto normal manufacturing tolerances. Thus, the regions illustrated in thefigures are schematic in nature and their shapes are not intended toillustrate the precise shape of a region of a device and are notintended to limit the scope of the invention.

FIG. 3 shows one embodiment of an LED component 40 according to thepresent invention comprising a submount 42 for holding an array of LEDchips, with the submount having die pads 44 and conductive traces 46 onits top surface. LED chips 48 are included that comprise the LED array,with each of the LED chips 48 mounted to a respective one of the diepads 44. Wire bonds 50 pass between the conductive traces 46 and each ofthe LED chips 48 with an electrical signal applied to each of the LEDchips 48 through its respective one of the die pads 44 and the wirebonds 50. Alternatively, LED chips 48 may comprise coplanar electricalcontacts on one side of the LED (bottom side) with the majority of thelight emitting surface being located on the LED side opposing theelectrical contacts (upper side). Such flip-chip LEDs can be mountedonto the submount 42 by mounting contacts corresponding to one electrode(anode or cathode, respectively) onto the die pad 44. The contacts ofthe other LED electrode (cathode or anode, respectively) can be mountedto the traces 46. An optional reflector 52 can be included that ismounted to submount around the LED chips 48, although in otherembodiments the reflector can be arranged in different locations and canbe shaped differently. The LED chips 48 in this embodiment can emit at asingle color, or be coated with a down-converting phosphor with eachtype of LEDs being connected at least into one series connectioncircuit. Alternatively, multiple types of LEDs can be simultaneouslymounted on the submount 42 with independent series circuits,respectively. An optical element 54 such as a lens is included over theLED chips 48.

The LED component 40 is shown with three LED chips 48, but it isunderstood that more LED chips can be included. At least some of the LEDchips 48 are interconnected in series to minimize the number of contactsto the LED component and to allow operation with suitable drivers at thedesired drive current, such as in the range of 50 to 150 mA. The “deadspace” between LED chips is smaller than prior LED components and istypically less than 0.50 mm. In one embodiment the spacing is 0.15 mm to0.01 mm depending on the mounting process, allowing for the LEDcomponents to be densely arranged on the top surface of submount 42.This allows for smaller sized devices that can have a form factor ofexisting lamps or even smaller, and can provide the ability to shape theoutput beam into a particular angular distribution.

FIG. 4a through 4d show another embodiment of a monolithic LED component60 according to the present invention comprising an array of LED chips62 mounted on the surface of a submount 64. At least some of the LEDchips 62 are interconnected in a series circuit, with the embodimentshown having LED chips coated with a phosphor converter interconnectedin one series circuit, and red emitting LEDs coupled on a second seriescircuit. In this embodiment the color space for the phosphor convertedLEDs comprises the quadrangle in the u′v′ 1976 CIE color space createdby the coordinates A with u′=0.13; v′=0.42, B with u′=0.13; v′=0.57, Cwith u′=0.26; v′=0.54, D with u′=0.22; v′=0.51, and E with u′=0.18;v′=0.42. Correspondingly, the red LEDs cover the color quadranglecreated by the coordinates E with u′=0.29; v′=0.54, F with u′=0.31;v′=0.56, G with u′=0.55; v′=0.55, and H with u′=0.53; v′=0.47. It isunderstood that different embodiments according to the present inventioncan have series interconnect circuits of the various chip types arrangedin many different ways, and as described below can compriseseries/parallel combination interconnect circuits.

The LED chips 62 are preferably mounted on a substantially planarsurface of the submount 64 and are arranged under a single optical lenselement. In the embodiment shown, the component 60 emits white light ata desired color point and color rendering index as combination of lightfrom the various LEDs, and simultaneously emits the desired luminousflux at high efficacy.

The LEDs chips 62 can have many different semiconductor layers arrangedin different ways and can emit many different colors in differentembodiments according to the present invention. LED structures,features, and their fabrication and operation are generally known in theart and only briefly discussed herein. The layers of the LEDs chips 62can be fabricated using known processes with a suitable process beingfabrication using metal organic chemical vapor deposition (MOCVD). Thelayers of the LED chips generally comprise an active layer/regionsandwiched between first and second oppositely doped epitaxial layersall of which are formed successively on a growth substrate. LED chipscan be formed on a wafer and then singulated for mounting in a package.It is understood that the growth substrate can remain as part of thefinal singulated LED or the growth substrate can be fully or partiallyremoved.

It is also understood that additional layers and elements can also beincluded in the LED chips 62, including but not limited to buffer,nucleation, contact and current spreading layers as well as lightextraction layers and elements. The active region can comprise singlequantum well (SQW), multiple quantum well (MQW), double heterostructureor super lattice structures. The active region and doped layers may befabricated from different material systems, with preferred materialsystems being Group-III nitride based material systems. Group-IIInitrides refer to those semiconductor compounds formed between nitrogenand the elements in the Group III of the periodic table, usuallyaluminum (Al), gallium (Ga), and indium (In). The term also refers toternary and quaternary compounds such as aluminum gallium nitride(AlGaN) and aluminum indium gallium nitride (AlInGaN). In a preferredembodiment, the doped layers are gallium nitride (GaN) and the activeregion is InGaN. In alternative embodiments the doped layers may beAlGaN, aluminum gallium arsenide (AlGaAs) or aluminum gallium indiumarsenide phosphide (AlGaInAsP).

The growth substrate can be made of many materials such at sapphire,silicon carbide, aluminum nitride (AlN), gallium nitride (GaN), with asuitable substrate being a 4H polytype of silicon carbide, althoughother silicon carbide polytypes can also be used including 3C, 6H and15R polytypes. Silicon carbide has certain advantages, such as a closercrystal lattice match to Group III nitrides than sapphire and results inGroup III nitride films of higher quality. Silicon carbide also has avery high thermal conductivity so that the total output power ofGroup-III nitride devices on silicon carbide is not limited by thethermal dissipation of the substrate (as may be the case with somedevices formed on sapphire). SiC substrates are available from CreeResearch, Inc., of Durham, N.C. and methods for producing them are setforth in the scientific literature as well as in a U.S. Pat. Nos. Re.34,861; 4,946,547; and 5,200,022.

The LED chips 62 can also comprise a conductive current spreadingstructure and wire bond pads on the top surface, both of which are madeof a conductive material and be deposited using known methods. Somematerials that can be used for these elements include Au, Cu, Ni, In,Al, Ag or combinations thereof and conducting oxides and transparentconducting oxides. The current spreading structure can compriseconductive fingers arranged in a grid on the LED chips 62 with thefingers spaced to enhance current spreading from the pads into the LED'stop surface. In operation, an electrical signal is applied to the padsthrough a wire bond as described below, and the electrical signalspreads through the fingers of the current spreading structure and thetop surface into the LED chips 62. Current spreading structures areoften used in LEDs where the top surface is p-type, but can also be usedfor n-type materials.

Each of the LED chips 62 can be coated with one or more phosphors withthe phosphors absorbing at least some of the LED light and emitting adifferent wavelength of light such that the LED emits a combination oflight from the LED and the phosphor. In one embodiment according to thepresent invention the white emitting LEDs chips 62 have an LED thatemits light in the blue wavelength spectrum and the phosphor absorbssome of the blue light and re-emits yellow. The LED chips 62 emit awhite light combination of blue and yellow light. In one embodiment thephosphor comprises commercially available YAG:Ce, although a full rangeof broad yellow spectral emission is possible using conversion particlesmade of phosphors based on the (Gd,Y)₃(Al,Ga)₅O₁₂:Ce system, such as theY₃Al₅O₁₂:Ce.(YAG). Other yellow phosphors that can be used for whiteemitting LED chips include:

Tb_(3-x)RE_(x)O₁₂:Ce(TAG); RE=Y, Gd, La, Lu; or

Sr_(2-x-y)Ba_(x)Ca_(y)SiO₄:Eu.

The LED chips 62 emitting red light can comprise LED structures andmaterials that permit emission of red light directly from the activeregion. Alternatively, in other embodiments the red emitting LED chips62 can comprise LEDs covered by a phosphor that absorbs the LED lightand emits a red light. Some phosphors appropriate for this structurescan comprise:

Red

Lu₂O₃:Eu³⁺

(Sr_(2-x)La_(x))(Ce_(1-x)Eu_(x)) O₄

Sr₂Ce_(1-x)Eu_(x)O₄

Sr_(2-x)Eu_(x)CeO₄

SrTiO₃:Pr³⁺,Ga³⁺

CaAlSiN₃:Eu²⁺

Sr₂Si₅N₈:Eu²⁺

The LED chips 62 can be coated with a phosphor using many differentmethods, with one suitable method being described in U.S. patentapplication Ser. Nos. 11/656,759 and 11/899,790, both entitled “WaferLevel Phosphor Coating Method and Devices Fabricated Utilizing Method”,and both of which are incorporated herein by reference. Alternativelythe LEDs can be coated using other methods such an electrophoreticdeposition (EPD), with a suitable EPD method described in U.S. patentapplication Ser. No. 11/473,089 entitled “Close Loop ElectrophoreticDeposition of Semiconductor Devices”, which is also incorporated hereinby reference. It is understood that LED packages according to thepresent invention can also have multiple LEDs of different colors, oneor more of which may be white emitting.

The submount 64 can be formed of many different materials with apreferred material being electrically insulating, such as a dielectricelement, with the submount being between the LED array and the componentbackside. The submount can comprise a ceramic such as alumina, aluminumnitride, silicon carbide, or a polymeric material such as polymide andpolyester etc. In the preferred embodiment, the dielectric material hasa high thermal conductivity such as with aluminum nitride and siliconcarbide. In other embodiments the submount 64 can comprise highlyreflective material, such as a reflective ceramic or metal layers likesilver, to enhance light extraction from the component. In otherembodiments the submount 64 can comprise a printed circuit board (PCB),alumina, sapphire or silicon or any other suitable material, such asT-Clad thermal clad insulated substrate material, available from TheBergquist Company of Chanhassen, Minn. For PCB embodiments different PCBtypes can be used such as standard FR-4 PCB, metal core PCB, or anyother type of printed circuit board.

It is understood that LED components according to the present inventioncan be fabricated using a method that incorporates submount panel orwafer comprising a plurality of submounts. Each of the submounts 64 canbe formed with its own array of LEDs and optical elements 66 such thatmultiple LED components 60 can be formed across the submount panel.Multiple LED components 60 can then be singulated from the submountpanel. Each submount 64 may also comprise a more complex combination ofelements such as a plurality of “submount” assemblies which are mountedon a planar surface of submount. As more fully described below, thesubmount assemblies can have different functionalities such as providingESD protection for the various LED chips.

The size of the submount 64 in LED package 60 can vary depending oncertain factors such as the size and number of LEDs. In one embodiment,the sides of the submount can be approximately 12 mm by 13 mm. It isfurther understood that the submount 64 can have other shapes includingcircular, oval, rectangular, hexagonal or other multiple sided shapes.

Referring now to FIG. 5, the top surface of the submount 64 is shownhaving planar surface with patterned conductive features 68 that caninclude die attach pads 70 and interconnecting conductive traces 72.These features 68 provide conductive paths for electrical connection tothe LED chips 62 (shown in FIGS. 4a to 4c ) using known contactingmethods. Each of the LED chips 62 can be mounted to a respective one ofthe attach pads 70 using known methods and material mounting usingconventional solder materials that may or may not contain a fluxmaterial. The LED chips 62 can similarly be mounted and electricallyconnected to the conductive traces 72 using known surface mount or wirebonding methods depending on the geometry of the LED chips 62.Alternatively, flip chip LEDs can be mounted as describe above on theattach pads and conductive traces.

The attach pads 70 and interconnecting traces 72 can comprise manydifferent materials, such as metals or other conductive materials, andin one embodiment they can comprise copper deposited using knowntechniques such as plating. In one typical deposition process a titaniumadhesion layer and copper seed layer are sequentially sputtered onto asubstrate. Then, approximately 75 microns of copper is plated onto thecopper seed layer, although different metal thicknesses may be used. Theresulting copper layer being deposited can then be patterned usingstandard lithographic processes. In other embodiments the layer can besputtered using a mask to form the desired pattern.

In other embodiments according to the present invention some or all ofthe features 68 can comprise other additional materials beyond copper.For example, the die attach pads can be plated or coated with additionalmetals or materials to the make them more suitable for mounting one ofthe LED chips 62. The attach pads can be plated with adhesive or bondingmaterials, or reflective and barrier layers.

As described above, the LED chips 62 are interconnected in two serialcircuits comprising phosphor coated LED chips and red emitting LEDchips, respectively. The LED component comprises bond pads for applyinga respective electrical signal to the white and red emitting LEDs. Asbest shown in FIG. 4b , first and second bond pads 74, 76 are providedon the surface of the submount 64 for applying an electrical signal tothe serially red LED chips of the LED array 62. Third and fourth bondpads 78, 80 are also provided for applying an electrical signal to theserially connected phosphor coated LED chips of the LED array 62. TheLED component can include markings to assist in making the correctelectrical connection with the proper bond pads for the red LED chipsdesignated R1 and R2, and the bond pads for the white emitting LEDdesignated B1 and B2. The conductive traces 72 provide the interconnectscheme for the red and blue serial connected circuits, and in oneembodiment, the interconnect scheme provides interconnections in asingle layer, with less than two traces running between the LEDs.

Electrical signals can be applied to the LED component 60 by providingexternal electrical contact to the first, second, third and fourth bondpads, such as by wire or ribbon bonding or other connection methods suchas the soldering of leads, special connectors or mounting the LEDcomponent to conductive paths on for example, a PCB. In the embodimentshown the LED component 60 is arranged for mounting using surface mounttechnology. The LED 60 comprises first, second, third and fourth surfacemount pads 82, 84, 86, 88 (best shown in FIG. 4d ) that can be formed onthe back surface of the submount 64, at least partially in alignmentwith its corresponding one of bond pads 74, 76, 78, 80 on the submount'sfront side. Conductive vias 90 are formed through the submount 64between the corresponding surface mount and bond pads, such that when asignal is applied to the surface mount pads 82, 84, 86, 88 it isconducted to its corresponding bond pad through its vias. The surfacemount pads 82, 84, 86, 88 allow for surface mounting of the LED package60 with the electrical signal to be applied to the LED component appliedto the surface mounting pads. The vias 90 and surface mount pads 82, 84,86, 88 can be made of many different materials deposited using differenttechniques, such as those used for the attach and bond pads.

It is understood that the surface mount pads 82, 84, 86, 88 and vias 90can be arranged in many different ways and can have many differentshapes and sizes. Other embodiments can use structure other than vias,including one or more conductive traces on the surface of the submountbetween the mounting pads and contact pads, such as along the sidesurface of the submount.

A solder mask can also be included on the submount's top or bottomsurface at least partially covering the conductive traces 72, portionsof the other conductive features or portions of the ceramic surface. Thebond pads and die attach pads are typically left uncovered, with thesolder mask protecting the conductive traces 72 and other coveredfeatures during subsequent processing steps and in particular mountingthe LED chips 72 to the die attach pads 70. During these steps there canbe a danger of solder or other materials depositing in undesired areas,which can result in damage to the areas or result in electricalshorting. The solder mask serves as an insulating and protectivematerial that can reduce or prevent these risks.

The LED component 60 can also comprise elements to protect againstdamage from electrostatic discharge (ESD), and can be on or off thatsubmount 64. Different elements can be used such as various verticalsilicon (Si) Zener diodes, different LEDs arranged in parallel andreverse biased to the LED chips 62, surface mount varistors and lateralSi diodes. In the embodiments using a Zener diode, it can be mounted tothe separate attach pad using known mounting techniques. The diode isrelatively small so that it does not cover an excessive area on thesurface of the submount 64, and when utilizing groups of LEDs coupled inseries only one ESD element is needed for each series group.

It is desirable to have the LED chips 62 densely arranged on thesubmount 64 to minimize the size of the submount 64 and the footprint ofthe component, and to enhance color mixing in those embodiments havingLED chips 62 emitting different colors of light. For LED chips 62 thatare close to one another, however, heat from the LED chips 62 can spreadto adjacent LED chips 62 or can accumulate in a concentrated area of thesubmount 64 below the LED chips 62. To enhance dissipation of heatgenerated by the LED chips 62 during operation the LED component 60 cancomprise integrated features to enhance thermal dissipation. One way toenhance thermal dissipation on the front side of the submount 64, is tohave die attach pads that are thermally conductive and extend on thefront surface of the submount 64 beyond the edge of the LED chips. Heatfrom each of the LED chips can spread into its die attach pad and beyondthe width of the extended die pads providing a larger surface area todissipate heat. Larger die pads, however, can be a limiting factor onhow close the LEDs can be to one another.

In some embodiments, the LED chips can remain densely arranged and thethermal dissipation from the LED chips 62 in component 60 can beenhanced by having die attach pads 70 and interconnected traces 72 madeof an electrically and thermally conductive material. During operationof the component, electrical signals can be applied through the attachpads and traces 70, 72, and heat can likewise spread from the LED chipsinto the attach pads and traces 70, 72 where it can dissipate or beconducted through the submount. Many different electrically andthermally conductive materials can be used, with a preferred materialbeing a metal such as copper.

Referring now to FIG. 4d , to further enhance thermal dissipation LEDcomponent 60 can further comprise a neutral metalized pad 92 on the backsurface of the submount 64. In regards to metalized pad 92, neutralrefers the pad 92 as not being electrically connected to LED chips orthe features 68. The metalized pad 92 is preferably made of a heatconductive material and is preferably in at least partial verticalalignment with the LED chips 62. Heat from the LED chips that does notspread through the attach pads and traces 70, 72 can be conducted intothe submount 64 directly below and around the LED chips 62. Themetalized pad 92 can assist with heat dissipation by allowing this heatbelow and around the LED chips 62 to spread into the metalized pad 92from where it can dissipate or be more readily conducted to suitableheat sinks. The pad 92 is shown as being rectangular, but it isunderstood that it can have many different shapes and sizes and cancomprise a plurality of pads having different shapes and sizes. Heat canalso conduct from the top surface of the submount 64, through the vias90, where the heat can spread into the first, second, third and fourthmounting pads 82, 84, 86, 88 where it can also dissipate.

An optical element or lens 66 can be formed on the top surface of thesubmount 64, over the LED chips 62, to provide both environmental and/ormechanical protection and beam shaping while simultaneously aiding thelight extraction from the LEDs 62 and shaping of the light beam. Thelens 66 can be in different locations on the submount 64 with the lens66 located as shown in alignment with the center of the array of LEDchips being at approximately the center of the lens base. In someembodiments the lens 66 is formed in direct contact with the LED chips64 and the top surface 64. In other embodiments there may be anintervening material or layer between the LED chips 64 the lens 66 suchas a waveguide or air gap. Direct contact to the LED chips 64 providescertain advantages such as improved light extraction and ease offabricating.

In one embodiment, the lens 66 can be overmolded on the submount 64 andLED chips 62 using different molding techniques, and the lens 66 can beof many different shapes depending on the desired shape of the lightoutput. One suitable shape as shown is hemispheric, with some examplesof alternative shapes being ellipsoid bullet, flat, hex-shaped andsquare. Hemispheric lenses can provide for an essentially lambertianemission with 120 degrees FWHM, while the other optical lenses can haveother shapes to provide for different emission patterns at differentangles.

For hemispheric embodiments, many different lens sizes can be used, withtypical hemispheric lenses being greater than 5 mm in diameter, with oneembodiment being greater approximately 11 mm. The preferred LED arraysize to lens diameter ratio should be less than approximately 0.6, andpreferably less than 0.4. For such hemispheric lenses the focal point ofthe lens shall be essentially at the same horizontal plane as theemission region of the LED chips.

In yet other embodiments, the lens can have a large diameter of aboutthe same or larger than the distance across or width of the LED array.For circular LED array the diameter of the lens can be approximately thesame as or larger that the diameter of the LED array. The focal pointfor such lenses is preferably below the horizontal plane created by theemitting region of the LED chips. The advantage of such lenses is theability to spread the light over larger solid emission angles andtherefore allow for a broader illuminated area.

Many different materials can be used for the lens 66 such as silicones,plastics, epoxies or glass, with a suitable material being compatiblewith molding processes. Silicone is suitable for molding and providessuitable optical transmission properties. It can also withstandsubsequent reflow processes and does not significantly degrade overtime. It is understood that the lens 66 can also be textured or coatedwith anti-reflection coatings to improve light extraction or can containmaterials such as phosphors or scattering particles.

In one embodiment a molding process is used that simultaneously formslenses 66 over a multitude of LED arrays on a submount panel. One suchmolding process is referred to as compression molding wherein a mold isprovided having a plurality of cavities each of which has an invertedshape of the lens. Each cavity is arranged to align with a respectiveone of the LEDs arrays on the submount panel. The mold is loaded with alens material in liquid form filling the cavities, with the preferredmaterial being liquid curable silicone. The submount panel can be movedtoward the cavity with each of the LEDs arrays being embedded in theliquid silicone within one a respective one of the cavities. In oneembodiment a layer of silicone can also remain between adjacent lensesthat provides a protective layer over the top surface of the submount.The liquid silicone can then be cured using known curing processes. Thepanel can then be removed from the mold and the panel can comprise aplurality of lenses, each of which is over a respective one of the LEDarrays 62. The individual LED components can then be separated orsingulated from the submount panel, using known techniques.

Other embodiments according to the present invention can comprisedifferent features to enhance thermal dissipation. FIGS. 6a though 6 cshow another embodiment of an LED component 100 according to the presentinvention comprising an LED array 102 mounted to a submount 104, with anoptical element or lens 106 over the LED array 102, all similar to thecorresponding elements in the LED component 60 described above in FIGS.4a through 4d . Conductive vias 108 are included that pass through thesubmount 104 to provide electrical connection between the bond pads 110and surface mount pads 112. This allows for surface mounting of the LEDcomponent, but it is understood that other features can be included toallow for other mounting techniques. The LED component 100 furthercomprises neutral metalized pad 114 to assist in thermal dissipation asdescribed above.

To further assist in heat dissipation in LED component 100, the submount104 can include additional heat features incorporated within thesubmount. These features can be used in submounts made of many differentmaterials, but are particularly applicable to ceramic submounts. Theadditional features can comprise a heat spreading layer 116 internal tothe submount 104 but preferably not electrically connected to the vias108. The layer 116 is preferably arranged below the LED array 102 suchthat heat from the array 102 spreads into the layer 116. The layer 116can be made of many different thermally conductive materials, includingbut not limited to copper, silver or a combination thereof. The LEDcomponent can also comprise partial thermal vias 118 running between theheat spreading layer 116 and the neutral metalized pad 114. In theembodiment shown, the partial thermal vias 118 do not protrude past thelayer 116 to the top surface of the submount 104 to maintain a flatmounting surface for the LED array 104 and its corresponding mountingpads. It is understood however, that in some embodiment the vias canprotrude at least partially above the heat spreading layer 116.

The layer 116 and partial vias 118 can be formed within the submountusing different methods, with one suitable utilizing high or lowtemperature co-fired ceramic technology or multilayer thick filmpost-firing technology. In those embodiments where the layer 116 is madeof copper or silver, thick film co-firing or post-firing process can beused due to high thermal conduction nature of these materials, to yieldthe desired configuration. Other fabrication processes to form thespreading layer 116 and vias 118 can be through multilayer printedcircuit board and flexible circuit board technology, generally known inthe industry.

FIGS. 7 and 8 show additional embodiments of monolithic LED componentsaccording to the present invention with a different shaped lens. The LEDcomponent 140 in FIG. 6 comprises LED chips 142 mounted in an array to asubmount 144, with a flat optical lens covering the LED chips. The LEDcomponent 150 in FIG. 7 comprises LED chips 152 mounted in an array on asubmount 154, with an aggregate optical lens 156 over the LED chips 152.The aggregate lens 156 includes a plurality of convex optical featuresto control the light extraction from the LED array and shape the emittedlight into particular beam shapes and emission angles. In otherembodiments the aggregate lens can include concave optical features, ora combination of convex and concave features, such as a Fresnel lens.

Other monolithic LED components according to the present invention canincorporate a number of different features such as an optical fiber,mirror, reflector, scattering surface or lens, or combination thereof.These features can act to direct or otherwise modify the distribution oflight from the component. The lens arrangement of the LED component 60is also easily adapted for use with secondary lens or optics that can beincludes over the lens by the end user to facilitate beam shaping. Thesesecondary lenses are generally known in the art, with many of them beingcommercially available.

As mentioned above, the LED chips in the LED array are preferablyarranged with the interconnecting electrical traces in a way to providefor dense packaging of the emitters on the submount, with thenon-emitting space between the LED emitters minimized. The space canvary in different embodiments and can vary between LED chips in oneembodiment. The distance between the LED chips can range from 5 micronor less, to 500 microns or more. In one embodiment, the space is 150microns or less.

In some embodiments the emitters are arranged in an array on thesubmount surface in a substantially symmetrical two dimensional layout.In one of these embodiments the LEDs in the array are densely arrangedin a substantially spherical shape. For LED arrays having groups of LEDsemitting at different colors of light an symmetric pattern isparticularly applicable to smaller LEDs in the LED array, wheredifferent colors can be intermixed in the array to achieve the desiredcolor mixing. For arrays having larger LEDs, an asymmetric array mayenhance color mixing.

In other embodiments the LEDs emitting at a particular color of lightcan be arranged with respect to the LEDs emitting at other colors oflight in a systematic geometrical order. In one such embodiment, theLEDs of different colors of light can be arranged in substantiallycircular arrays of approximately the same inscribed area for each colorgroup and the groups of LEDs can be radially offset with respect to eachother.

Different embodiments of the LED component 60 can have LED arrays withdifferent sized LEDs and different numbers of LEDs, with certain factorsapplicable in determining the desired arrangement for both. For largerLED sizes the desired luminous flux can be provided with fewer LEDs, butin LED components utilizing LEDs emitting different colors of light,larger LEDs can result in ineffective color mixing. To improve colormixing, larger numbers of smaller LEDs can be used. This, however, canresult in more complex interconnection schemes.

The LED arrays can also have LEDs that are substantially the same size.In one embodiment the LED chip size area is less than 500 microns, whilein other embodiments the chip size area is greater than 500 microns,such as a chip size of approximately 700 microns. The edges of the LEDemitters can be different lengths, with one embodiment having lengths ofapproximately 0.4 to 0.7 mm. Many different numbers of LED chips can beincluded in the array, and in some embodiments the number of LED chipsis greater than 20, but fewer LED chips can also be used. The LEDcomponent 60 comprises 26 LED chips of which 20 are white emitting LEDchips and 6 are red emitting LED chips.

As discussed above, at least some of the LED emitters are electricallyconnected in series to provide for at least one serial circuit, with theLED array component capable of emitting multiple colors of light,including white light. In some embodiments having arrays with groups ofLEDs emitting different colors of light (e.g. white and red), the LEDsof each color are electrically connected in series. As discussed above,the LED component 60 can provide for respective electrical connectionsto these serial circuits to control the operating voltage and currentfor each circuit separately. Such electrical connection pads can beprovided on the front side, backside, or both. Backside electrodesprovide for SMT mounting capability on PCB boards.

FIG. 9 shows a schematic of one embodiment of two series connected LEDcircuits that can be used for the array of LED chips shown in FIGS. 4athrough 4d . The first series circuit 160 comprises twenty (20) phosphorcoated LED chips 162 (only 8 shown) that can comprise serially connectedblue emitting LEDs coated with one or more phosphor. The combined LEDand phosphor emission convert the blue to green, and/or yellow spectralranges, with the LED emitting a mixed light combination of light fromthe LED and phosphor. The second series 170 comprises 6 seriallyconnected red emitting LEDs chips 172. Respective electrical signals canbe applied to the first and second circuit 160 and 170 so that each canbe driven by a different drive current.

The red LED chips can provide direct emission without the use of aconverter material. The phosphor coated and red LED chips 162 and 172are shown in the schematic as physically separate for ease ofunderstanding, but when physically placed in the array the red and whiteLED chips can be randomly mixed. The mixed emission from the first andsecond series connected circuits can be cool or warm white light. Theemission can have different color renderings, with one embodiment havinga color rendering index of greater than 85.

Allowing respective electrical signals to be applied to the phosphorcoated and red LED chips within with the array allows for independentelectrical control of the different groups of LED colors. In particularthis can allow for independent drive currents to the different groups.In one embodiment, the red LED chips can have a different temperaturesensitivity compared to the phosphor coated LED chips, and astemperature goes up it can be necessary to increase the drive current tothe red LED chips to maintain the desired luminous flux or reduce thedrive current through the phosphor coated LEDs, respectively. Anytemperature sensitivity with the phosphor coated LED chips can also becompensated for by varying drive current with temperature. This allowsfor the LED array to emit at or near the desired color point throughdifferent temperatures. In other embodiments, the likely temperaturerange for the LED components can be known. The LED components can thenbe designed for that range such that the drive conditions are present.

In other embodiments, different combinations of phosphor coated and redemitting LEDs can be used to achieve the desired color rendering index.In the embodiment having 20 phosphor coated emitting LED chips and 6 redemitting LED chips, the phosphor coated LED chips are preferably coatedwith a phosphor with an emission characteristics corresponding to u′ ofabout 0.220 and v′ of about 0.560 in the 1976 CIE color coordinatesystem. The corresponding mixed white light emission from the LEDcomponent has a color temperature of about 2800K and a color renderingindex >85. For phosphor coated LED chips coated with a phosphor with anemission corresponding to u′ of about 0.206 and v′ of about 0.560, 18white LED chips can be combined with 8 red emitting LED chips to reachthe desired color temperature and color render index. This correspondsto phosphor coated LED chips that emit closer to the black body locus(BBL) on the CIE curve needing fewer red emitting LEDs, while converselyphosphor coated LED chips emitting further from the BBL may require agreater red luminous flux or a greater number of red emitting LEDs toreach a white emission on the black body locus. It is understood thatother ratios and color points of phosphor coated and red LED chips canalso be used to target different white emission properties.

As discussed above, the different number of series connected LED chipcircuits can impact the operating voltage and current of LED componentsaccording to the present invention. FIG. 10 shows a graph comparingdifferent 1000 lumen LED component arrangements for commerciallyavailable EZ700 and EZ1000 EZBright™ LED chips provided by Cree, Inc.Using the EZ700 with twenty-four (24) chips in a single seriesconnection circuit, operational current of 0.175 amps and voltage of76.8 volts can be used. This provides the lowest cost driver solution.As the number of series connected circuits increase, the driver currentrequired also increases while the driver voltage decreases. Thistypically increases the cost of the drivers, but the additional seriesconnected circuits allow for greater control over the LED chips in theLED component. The similar trade-off in voltage or current requirementsverses emission control applies for LED components having twelve (12)EX1000 LED chips.

The LED arrays according to the present invention can also comprisearrays of LEDs chips arranged in a serial/parallel interconnection. FIG.11 shows one embodiment of a series/parallel interconnection 180comprising eighteen (18) white LED chips 182 arranged in a three by sixserial/parallel interconnection, comprising three sets of six LED chips182 connected in series. The three sets are then coupled in parallel.This serial/parallel arrangement can lower the voltage necessary todrive the LED, while still allowing for reduced drive currents. Theinterconnection 180 can also comprise jumpers 184 or interconnectionnodes being placed after groups of one or more series connected LEDs andbetween the LEDs. The jumpers 184 allow for the electrical signalapplied to the LEDs to bypass a failed LED. For instance, if LED chip186 failed the electrical signal applied to the LEDs that follow inseries could be interrupted. By including bypass jumpers 184, theelectrical signal can bypass failed LED chip 186 through for examplejumper 188 so that the electrical signal can pass to the LED chipsfollowing in series from the failed LED chip 186.

FIG. 12 shows another embodiment of a series/parallel interconnection190 having two sets of nine LED chips 192 coupled in series, with thetwo sets coupled in parallel. Jumpers 194 are included to bypass failedLED chips. Different series/parallel interconnection can have differentarrangements including with the different series coupled LED chipshaving the same or different numbers of LED chips. For example, theeighteen (18) LED chips shown can have series LED circuits of five, sixand seven, with each of the series circuits coupled in parallel.

In other embodiments color sub-groups of LEDs can be provided thatcombine to achieve the particular color that would otherwise be providedby a single color group. For example, if it is desired to provide aparticular color emission from the first color group, the group cancomprise phosphor coated LEDs emitting at the particular desired colorline. A second color group comprises red emitting LEDs can be providedwith the resulting combined emission from the first and second groupsbeing at or near the desired emission on the black body line of the CIEcurve. Under certain circumstances it may be desirable to include two ormore serially connected sub-groups to achieve the color desired from oneof the first or second groups. By way of example, two color sub-groupscan be utilized to provide the emission of the first color group. If thedesired emission from the first group is at a particular color line, thefirst sub-group can emit light below the color line and the secondsub-group can emit light above the color line. The combination of lightfrom the sub-groups can provide the desired light that would otherwisebe provided by the first group.

The sub-groups can be coupled in series such that each can beindependently controlled to provide the desired luminous flux and colormixing, and to compensate for emission inefficiencies. In embodimentswhere the flux of the sub-groups is such that application of the sameelectrical signal results in the desired color point, the same signalcan be applied to each of the sub-groups.

The present invention is directed to many different LED chiparrangements with the individual LED chips either coated by a convertingphosphor or emitting light directly from their active region. In onealternative embodiment, a single or plurality of series connected LEDchip circuits can comprise LED chips wherein all are coated with asingle down-converting material. The mixed emission from the LED and thedown-converting material can be cool or warm light. In one embodiment,all the LED chips emitter are blue LEDs covered with phosphor.

It is understood that the LED chips in the arrays can be arranged as oneor more multiple multi-chip LED lamps as described in U.S. PatentPublication No. 2007/0223219 entitled “Multi-Chip Light Emitting Devicefor Providing High-CRI Warm White Light and Light Fixtures Including theSame”, the disclosure of which is incorporated by reference.

Another embodiment can comprise a single or plurality of seriesconnection LED circuits, with all the LED chips comprising LEDs beingcoated with two or more down-converting materials like a phosphor. Thecombined LED and phosphor emission can cover different spectral rangessuch as blue, green, yellow and red spectral ranges. The mixed emissioncan be cool or warm white light with a color point on the black bodylocus or within an 8-step Mac Adam ellipse thereof with high colorrendering index of greater that 85. The phosphor composition can be forexample selected from materials discussed above.

In still other embodiments of an LED component according to the presentinvention can comprise a plurality of series connection circuitscomprising LED chips that emit light directly from their active region,with at least one series circuit provided for red, green and blueemitting LEDs, respectively. In other embodiments series connected LEDscircuits can also be added emitting cyan, yellow and/or amber. The LEDcomponent preferably emits a white light combination of light from theseries circuits that has a high color rendering index of greater than85.

Still other embodiments can comprise different LED chips with LEDsemitting at different wavelengths. For example, in any of the LED chipconfigurations above in which at least one of the emitters comprises ashort wavelength emitter in conjunction with one or more phosphoremitters, an ultraviolet emitting LED can be used as the LED. Thisresults in the predominant emission component of the LED chips comingfrom the phosphor coating the ultraviolet LED. Each of the followingphosphors exhibits excitation in the UV emission spectrum, provides adesirable peak emission, has efficient light conversion, and hasacceptable Stokes shift:

Yellow/Green

(Sr,Ca,Ba)(Al,Ga)₂S₄:Eu²⁺

Ba₂(Mg,Zn) Si₂O₇:Eu²⁺

Gd_(0.46)Sr_(0.31)Al_(1.23)O_(x)F_(1.38):Eu²⁺ _(0.06)

(Ba_(1-x-y)Sr_(x)Ca_(y))SiO₄:Eu

Ba₂SiO₄:Eu²⁺

The LED components according to the present invention are particularlyapplicable to integration is solid state lighting luminares, and providefor surface mount or wire bond mounting in the luminares. The LEDcomponents provide an improvement in the lumens provided per cost, dueto the reduced assembly requirements and footprint in luminaries alongwith reduced driver costs as described above.

Although the present invention has been described in detail withreference to certain preferred configurations thereof, other versionsare possible. Therefore, the spirit and scope of the invention shouldnot be limited to the versions described above.

We claim:
 1. A monolithic light emitting diode (LED) package, comprising: an LED array generating light having a luminous flux greater than 800 lumens at a color temperature less than 3000 K, said array on a submount; patterned conductive features which connect said array to at least one bond pad, wherein said at least one bond pad is remote from said array; at least one via through said submount which connects said at least one bond pad to a surface mount pad; and a single lens coupled to said array, wherein a dead space between each LED is less than 0.50 mm, each LED in said LED array mounted on said patterned conductive features; wherein a first path of said patterned conductive features electrically interconnects a first group of LEDs emitting at a first color temperature and a second path of said patterned conductive features electrically interconnects a second group of LEDs emitting at a second color temperature different than said first color temperature such that said first and second groups are independently controllable, and wherein said LED array is configured to shape an output beam of the LED package.
 2. A monolithic light emitting diode (LED) package, comprising a carrier and an LED array capable of emitting light while being driven by a current of less than approximately 150 milli-Amps; wherein said LED array is mounted on patterned conductive features on the carrier, said patterned conductive features connecting at least a portion of said array to at least one bond pad, wherein said at least one bond pad is remote from said LED array, said package comprising at least one via through said carrier which connects said at least one bond pad to a surface mount pad, a first path of said patterned conductive features electrically interconnecting a first group of LEDs emitting at a first color temperature and a second path of said patterned conductive features electrically interconnecting a second group of LEDs emitting at a second color temperature such that said first and second groups are independently controllable, and wherein said LED array is configured on the carrier to shape an output beam of the LED package.
 3. The LED package of claim 2, wherein said LED array is capable of being driven by a current in the range of approximately 50 milli-Amps to less than approximately 150 milli-Amps.
 4. A monolithic light emitting diode (LED) package, comprising an array of LED chips on a submount, under a single hemispheric lens having a dimension being approximately the same as or larger than the width of said array, in a substantially non-rectangular layout; a heat spreading layer internal to said submount, wherein said heat spreading layer is electrically isolated from said array of LED chips; and at least one bond pad on said submount and external to said single hemispheric lens; wherein the focal point of said lens is below a horizontal plane approximated by the emitting regions of said LED chips, and wherein said array of LED chips shapes an output beam of the LED package.
 5. The LED package of claim 4, wherein said LED chips have a size of less than 500 microns.
 6. The LED package of claim 4, wherein said lens comprises a large diameter.
 7. The LED package of claim 4, wherein said LED chips are mounted on a substrate comprising FR4 board.
 8. A monolithic light emitting diode (LED) package, comprising an array of LED chips on a submount and under a single hemispheric lens in an asymmetric layout, wherein the focal point of said lens is below a horizontal plane approximated by the emitting regions of said LED chips, and wherein said array of LED chips is configured to shape an output beam of the LED package; a heat spreading layer internal to said submount and electrically isolated from said array of LED chips; and at least one bond pad on said submount and external to said single hemispheric lens.
 9. A monolithic light emitting diode (LED) package, comprising: an array of LED chips on a submount; patterned conductive features which connect said array to at least one bond pad, wherein said at least one bond pad is remote from said array, wherein each of said LED chips emits light at a first or second color, said LED chips emitting at said first color randomly on said submount in relation to said LED chips emitting at said second color, said array of LED chips under a single hemispheric lens; and at least one via through said submount which connects said at least one bond pad to a surface mount pad; wherein a first serial circuit comprises said LED chips emitting at said first color and a second serial circuit comprises said LED chips emitting at said second color, and wherein said array of LED chips is configured to shape an output beam of the LED package. 